Align android button to the screen center

Question

I was wondering if there is a chance to align the play button as from screenshot at the center of the screen. Unfortunately, I have only succeeded in doing such with the white space that I wish to remove. The whole code sample has been attached to the question upon request. This now illustrates the area, where two blocks must be separated with a constraint layout with a required button in the center

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/ROOT"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:background="#f5907c"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="0.5"
        android:orientation="vertical"
        android:clickable="true"
        android:focusable="true">

        <View
            android:id="@+id/dummyViewTop"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />

        <TextView
            android:id="@+id/top_clock"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:clickable="false"
            android:gravity="center"
            android:rotation="180"
            android:text="@string/DEFAULT_CLOCK_VALUE"
            android:textSize="90sp"
            android:textColor="@color/white"
            android:textStyle="bold"
            />

    </RelativeLayout>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
        <ImageButton
            android:id="@+id/CONTROL_BUTTON_RESET"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:background="@android:color/transparent"
            android:scaleType="center"
            android:src="@drawable/ic_baseline_reset_24"
            android:contentDescription="@string/reset_button_desc"
            />
    </androidx.constraintlayout.widget.ConstraintLayout>

    <RelativeLayout
        android:background="#2e3a52"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="0.5"
        android:orientation="vertical">

        <View
            android:id="@+id/dummyViewBottom"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />

        <TextView
            android:id="@+id/bottom_clock"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="@string/DEFAULT_CLOCK_VALUE"
            android:textSize="90sp"
            android:textColor="@color/white"
            android:textStyle="bold"
            />

    </RelativeLayout>

</LinearLayout>

Answer 1

you have to give a constraint properly to your button like this:

<androidx.constraintlayout.widget.ConstraintLayout
     android:layout_width="match_parent"
     android:layout_height="mate_parent">

     <TextView
         android:id = "@+id/textView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         app:layout_constraintTop_toTopOf="parent"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"/>
    
</androidx.constraintlayout.widget.ConstraintLayout>
      

Answer 2

I will solve this in this manner by making constraint layout as the root layout. It will flatten our view hierarchy and reduces the code complexity

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:id="@+id/ROOT"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

    
    <TextView
        android:background="#f5907c"
        android:id="@+id/top_clock"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:clickable="false"
        android:gravity="center"
        android:rotation="180"
        android:text="10:00"
        android:textSize="90sp"
        android:textColor="@color/white"
        android:textStyle="bold"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@id/bottom_clock"/>

    <TextView
        android:id="@+id/bottom_clock"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:gravity="center"
        android:text="10:00"
        android:background="#2e3a52"
        android:textSize="90sp"
        android:textColor="@color/white"
        android:textStyle="bold"
        app:layout_constraintTop_toBottomOf="@id/top_clock"
        app:layout_constraintBottom_toBottomOf="parent"/>
    <ImageView
       android:id="@+id/btn_setting"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/add_btn"
       app:layout_constraintTop_toTopOf="@id/bottom_clock"
       app:layout_constraintBottom_toTopOf="@id/bottom_clock"
       app:layout_constraintStart_toStartOf="parent"
       app:layout_constraintEnd_toStartOf="@id/btn_refresh"/>
    <ImageView
       android:id="@+id/btn_refresh"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/add_btn"
       app:layout_constraintTop_toTopOf="@id/bottom_clock"
       app:layout_constraintBottom_toTopOf="@id/bottom_clock"
       app:layout_constraintEnd_toEndOf="parent"
       app:layout_constraintStart_toEndOf="@id/btn_setting"/>
    

 </androidx.constraintlayout.widget.ConstraintLayout>

I suggest you to explore Constraint layout some time

Answer 3

Try this

<androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
        <ImageView
            android:id="@+id/CONTROL_BUTTON_RESET"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/ic_baseline_reset_24"
            android:scaleType="center"

            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            />
</androidx.constraintlayout.widget.ConstraintLayout>

this should make your button center in the middle of the screen, provided your ConstratintLayout occupies the whole screen.

Also, don't use ImageButton, use an ImageView and apply a click listener to it.